Process for the reduction of acidic contaminates in fluorinated hydrocarbons

ABSTRACT

The present invention relates to processes for reducing the concentration of acidic impurities HF, HCl, HBr, HI, HNO 3  and H 2 SO 4  in fluorinated hydrocarbons. The process involves: (i) contacting the fluorinated hydrocarbon with a phosphorous oxyacid salt, and (ii) recovering the fluorinated hydrocarbon having reduced concentration of, or substantially free of, said acidic contaminant, provided that said fluorinated hydrocarbon is not CF 3 CH 2 CF 3  or CF 3 CHFCF 3 .

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a process for reducing theconcentration of acidic contaminates in fluorinated hydrocarbons bycontact with a phosphorous oxyacid salt.

[0003] 2. Description of Related Art

[0004] Chlorine- and bromine-substituted fluorinated hydrocarbons havelong found applications as refrigerants, blowing agents, propellants,solvents, and fire extinguishants. However, dissociation of thesematerials in the atmosphere has been linked to depletion ofstratospheric ozone. Many of these materials have been replaced byfluorinated hydrocarbons that contain only carbon, hydrogen, andfluorine (i.e., hydrofluorocarbons or HFC's). Examples of suchhydrofluorocarbons include 1,1,1,2,3,3,3-heptafluoropropane (CF₃CHFCF₃or HFC-227ea, an aerosol propellant and fire extinguishant),1,1,1,3,3,3-hexafluoropropane (CF₃CH₂CF₃ or HFC-236fa, a fireextinguishant and refrigerant), 1,1,1,3,3-pentafluoropropane (CF₃CH₂CHF₂or HFC-245fa, a polymer foam blowing agent), and1,1,1,2-tetrafluoroethane (CF₃CH₂F or HFC-134a, a refrigerant andaerosol propellant).

[0005] Commercial manufacturing processes for hydrofluorocarbons ofteninvolve addition of HF, an inorganic acid, to olefins. For example,HFC-227ea is prepared by addition of HF to hexafluoropropene (see U.S.Pat. No. 6,281,395). Other processes involve reacting HF withchlorinated hydrocarbons such as chloroolefins, chloroalkanes, orpartially fluorinated chlorocarbons. For example, HFC-236fa is preparedby reacting HF with 1,1,1,3,3,3-hexachloropropane and HFC-245fa isprepared by reacting HF with 1,1,1,3,3-pentachloropropane (see U.S. Pat.No. 6,291,730). In this type of exchange process, HCl, an inorganicacid, is formed as a by-product of the substitution of fluorine forchlorine. Other hydrofluorocarbon manufacturing processes involvereplacement of a chlorine substituent in a chlorofluorocarbon or ahydrochlorofluorocarbon with a hydrogen substituent by reaction withhydrogen with elimination of HCl. For example, HFC-134a is prepared byreaction of hydrogen with 1,1-dichloro-1,2,2,2-tetrafluoroethane (seeU.S. Pat. No. 5,208,397) and HFC-236fa is prepared by reaction ofhydrogen with 2,2-dichloro-1,1,1,3,3,3-hexafluoropropane (seeInternational Patent Application No. 96/17,813).

[0006] Fluoroolefins such as hexafluoropropene (C₃F₆, HFP) and1,1,3,3,3-pentafluoro-1-propene (CF₃CH═CF₂, HFC-1225zc) are anotherclass of fluorinated hydrocarbons of commercial interest; thesecompounds are often useful as polymer intermediates. Fluoroolefins maybe prepared under conditions where acidic contaminants may be present.For example, U.S. Pat. No. 5,057,634 discloses a process for preparationof hexafluoropropene comprising as a final step hydrodehalogenatingCF₃CClFCF₃ in the presence of hydrogen and a catalyst. U.S. Pat. No.6,093,859 discloses a process for producing HFC-1225zc involvingdehydrofluorinating HFC-236fa at an elevated temperature in the vaporphase over a catalyst.

[0007] The crude product in the aforementioned processes may becontaminated with hydrogen chloride (HCl) and/or hydrogen fluoride (HF).Removal of HCl and HF is usually accomplished by distillation, buttraces of these acidic contaminants often remain in the product. Evenafter distillation, fluorinated hydrocarbons may remain contaminatedwith HF or HCl due to the formation of azeotropes or azeotrope-likecompositions; that is constant-boiling mixtures that behave as a singlesubstance. For example, it has been disclosed that HFC-227ea forms anazeotrope with HF (see U.S. Pat. No. 6,376,272) and HFC-236fa forms anazeotrope with HF (see U.S. Pat. No. 5,563,304). These acidiccontaminants must be removed from the hydrofluorocarbons prior tocommercial use.

[0008] It is well-known that acidic contaminants in perhalogenatedfluorocarbons (e.g., CCl₂F₂) may be removed by treatment with a strongbase such as sodium hydroxide without degradation of the perhalogenatedfluorocarbon. However, substitution of one or more hydrogen substituentsin a saturated hydrocarbon by a halogen (i.e., fluorine, chlorine,bromine, or iodine) often increases the acidity of at least some of theremaining hydrogen substituents (see the discussion by Reutov,Beletskaya, and Butin on pages 51 to 58 in CH-Acids, Pergamon Press,Oxford, (1978)). Depending on the particular arrangement of hydrogen andhalogen substituents, exposure of a saturated partially halogenatedhydrocarbon to a base such as sodium hydroxide may result in facileelimination of the corresponding hydrogen halide from the halogenatedhydrocarbon by dehydrohalogenation, which is the elimination of hydrogenhalide from a saturated halogenated hydrocarbon to produce anunsaturated halogenated compound. The unsaturated compound so formed canbe acyclic (linear or branched) or cyclic, depending upon the startinghalogenated hydrocarbon.

[0009] Therefore, removal of acidic contaminants from saturatedhalogenated hydrocarbons by contacting mixtures of saturated halogenatedhydrocarbons and HF or HCl with strong bases, such as sodium hydroxide,potassium hydroxide, sodium carbonate, or potassium carbonate, mayresult in the formation of substantial amounts of unsaturated compounds(e.g., amounts greater than 5 weight per cent of the startinghalogenated hydrocarbon) due to elimination of hydrogen halide throughdehydrohalogenation. For example, as disclosed in the examples herein,contact of HFC-227ea with strong base gives some hexafluoropropene,contact of HFC-236fa with strong base gives some1,1,3,3,3-pentafluoro-1-propene, contact of HFC-245fa with strong basegives some 1,3,3,3-tetrafluoro-1-propene, contact of2,3-dichloro-1,1,1,3,3,3-pentafluoropropane (CF₃CHClCClF₂, HCFC-225da)with strong base gives some 2-chloro-1,1,3,3,3-pentafluoro-1-propene,and contact of 1,1,1,2,2,3,4,5,5,5-decafluoropentane (CF₃CF₂CHFCHFCF₃,HFC-43-10mee) with strong base gives some nonafluoropentenes.

[0010] U.S. Pat. No. 6,187,976 example 5 discloses a liquid phasefluorination process for CCl₃CH₂CCl₃. The product stream consisting ofHCFC-235fa (1-chloro-1,1,3,3,3-pentafluoropropane), HFC-236fa(1,1,1,3,3,3-hexafluoropropane), 1,1,3,3,3-pentafluoropropene, HF, HCl,and other minor products is passed through a caustic scrubber. Theacid-free product stream contains 25% 1,1,3,3,3-pentafluoropropene.

[0011] Because unsaturated fluorocarbons are frequently toxic, theirpresence in a hydrofluorocarbon product is undesirable. Removal of suchunsaturated compounds by distillation is often difficult due to the factthat they may have boiling points close to those of thehydrofluorocarbons or they may even form azeotropes or azeotrope-likemixtures with the hydrofluorocarbons. Thus, formation of unsaturatedimpurities during a neutralization process is not only a yield loss, butresults in the need for additional purification steps which add to theoverall cost of the manufacturing process.

[0012] Highly fluorinated olefins such as HFP and HFC-1225zc arewell-known to be reactive toward nucleophiles (e.g., the anionic portionof a compound such as sodium hydroxide where the hydroxide ion is thenucleophile). Therefore, removal of acidic contaminants from highlyfluorinated olefins by contacting mixtures of highly fluorinated olefinsand HF or HCl with strong bases, such as sodium hydroxide, potassiumhydroxide, sodium carbonate, or potassium carbonate, may result innucleophilic attack by hydroxide ion at the double bond with hydrolysis(i.e., replacement of the fluoride ion by hydroxide ion) of the olefinand formation of fluoride ions. This can result in a substantial yieldloss, such as a yield loss of greater than 5 weight percent of thestarting fluorinated olefin. World Intellectual Property Organizationpatent application publication no. WO 96/29,296 discloses a method forproducing fluoroalkanes by high-temperature pyrolysis ofchlorodifluoromethane in the presence of an alkane or fluoroalkane. Theproducts of said process are scrubbed with caustic soda prior toisolation (page 3, lines 3, 4, and 5); little fluoroolefins are observedin the products and apparently about 40% of the yield is not to usefulproducts.

[0013] There is an industry need for a process to remove acidiccontamination from saturated and unsaturated fluorinated hydrocarbons inwhich the dehydrohalogenation of saturated fluorinated hydrocarbons orhydrolysis of unsaturated fluorinated hydrocarbons is reduced. Thepresent invention meets that need.

BRIEF SUMMARY OF THE INVENTION

[0014] The present invention is a process for reducing the concentrationof acidic contaminates HF, HCl, HBr, HI, HNO₃ and H₂SO₄ in fluorinatedhydrocarbons and involves the steps of: (i) contacting the fluorinatedhydrocarbon with a phosphorous oxyacid salt such as orthophosphoric acidsalts, phosphorous acid salts, metaphosphoric acid salts, andpyrophosphoric acid salts, and (ii) recovering the fluorinatedhydrocarbon having reduced concentration of, or substantially free of,said acidic contaminant, provided that said fluorinated hydrocarbon isnot CF₃CH₂CF₃ or CF₃CHFCF₃. The contacting step of the present processis preferably carried out with the phosphorous oxyacid salt in aqueoussolution having a pH of no more than about 10. The present processresults in less than about 5 weight percent of the fluorinatedhydrocarbon being decomposed by dehydrohalogenation or by hydrolysisduring the contacting step and is an improvement over prior artprocesses for removing such acidic impurities from fluorinatedhydrocarbons.

DETAILED DESCRIPTION OF THE INVENTION

[0015] This invention provides a process for reducing the amount ofacidic contaminants from fluorinated hydrocarbons by contactingacid-contaminated fluorinated hydrocarbons with phosphorous oxyacidsalts.

[0016] As is well known in the art, when acidic contaminants arecontacted with phosphorous oxyacid salts, the acidic contaminant isconverted to the corresponding salt. The present inventors have foundthat when said contacting of the acidic contaminant with the phosphorousoxyacid salts is carried out in the presence of cyclic or acyclic,saturated or unsaturated fluorinated hydrocarbons, reduction orsubstantial removal of the quantity of acidic contaminant occurs withoutsubstantial dehydrohalogenation of the saturated fluorinated hydrocarbonor hydrolysis of the unsaturated fluorinated hydrocarbon. By “withoutsubstantial dehydrohalogenation of the saturated fluorinatedhydrocarbon” is meant that less than about 5 weight percent of thesaturated fluorinated hydrocarbon is converted to an unsaturatedfluorinated hydrocarbon. Preferably, less than about 0.5 weight percentof the saturated fluorinated hydrocarbon is converted to an unsaturatedfluorinated hydrocarbon. By “without substantial hydrolysis of theunsaturated fluorinated hydrocarbon” is meant that less than about 5weight percent of the unsaturated fluorinated hydrocarbon is convertedto other products by hydrolysis. Preferably, less than about 0.5 weightpercent of the unsaturated fluorinated hydrocarbon is converted to otherproducts by hydrolysis. By “substantial removal” or “substantially free”means that the present process produces a fluorinated hydrocarbonproduct containing 10 ppm-molar or less, preferably 1 ppm-molar or less,of acidic contaminants.

[0017] Phosphorous oxyacid salts of the present invention are: (i)orthophosphoric acid salts of the formula M_(n)H_(3-n)PO₄, wherein n isan integer from 1 to 3; (ii) phosphorous acid salts of the formulaM_(m)H_(2-m)(HPO₃), wherein m is 1 or 2; (iii) metaphosphoric acid saltsof the formula (MPO₃)_(z), wherein z is an integer from 1 to 6; and (iv)pyrophosphoric acid salts of the formula M_(k)H_(4-k)P₂O₇, wherein k isan integer from 1 to 4; wherein M is selected from the group consistingof NH₄, Li, Na, and K. Preferred phosphorous oxyacid salts of thepresent invention are orthophosphoric acid salts of the formulaM_(n)H_(3-n)PO₄, wherein n is an integer from 1 to 3, and M is selectedfrom the group consisting of NH₄, Na, and K. Owing to their availabilityand favorable solubility in water, mixtures of the potassium salts oforthophosphoric acid (K₃PO₄, K₂HPO₄, and KH₂PO₄) are the most preferredphosphorous oxyacid salts. Example salts of orthophosphoric acid includetribasic sodium phosphate (Na₃PO₄), dibasic sodium phosphate (Na₂HPO₄),monobasic sodium phosphate (NaH₂PO₄), tribasic potassium phosphate(K₃PO₄), dibasic potassium phosphate (K₂HPO₄), monobasic potassiumphosphate (KH₂PO₄), dibasic ammonium phosphate ((NH₄)₂HPO₄), monobasicammonium phosphate (NH₄H₂PO₄), tribasic lithium phosphate (Li₃PO₄),dibasic lithium phosphate (Li₂HPO₄), monobasic lithium phosphate(LiH₂PO₄), and their various hydrated salts. Other suitable saltsinclude mixed salts such as for example, sodium ammonium hydrogenphosphate (NH₄NaHPO₄). Example salts of pyrophosphoric acid suitableinclude potassium pyrophosphate (K₄P₂O₇) or sodium pyrophosphate(Na₄P₂O₇) or their mixtures with pyrophosphoric acid. Example salts ofmetaphosphoric acid include “sodium polyphosphate” (NaPO₃)_(p) or itsmixtures with metaphosphoric acid.

[0018] Mixtures of any of the aforementioned phosphorous oxyacid saltsmay also find utility in the present process.

[0019] The contacting step of the present invention may be carried outby passing a gaseous or liquid mixture of fluorinated hydrocarbon(s) andacidic contaminant(s) through a bed of substantially dry phosphorousoxyacid salt(s). The salt is consumed in the contacting step and ispreferably finely divided to ensure intimate contact with the mixture.In this embodiment, the mixture may be vaporized alone or in combinationwith an inert carrier gas such as nitrogen. Stirring and agitation ofthe bed may be carried out through use of known methods.

[0020] The contacting step of the present invention may also, and morepreferably, be carried out by contacting a gaseous or liquid mixture offluorinated hydrocarbon(s) and acidic contaminant(s) with an aqueoussolution of phosphorous oxyacid salt(s). The concentration ofphosphorous oxyacid salts in said aqueous solutions is not critical andis typically from about 1 percent by weight to about 20 percent byweight, preferably from about 3 percent by weight to about 10 percent byweight. Lower concentrations of salts may be volumetrically inefficientin removal of acid contaminants and higher concentrations may tend toform precipitates.

[0021] Said aqueous solutions may be prepared by adding the desiredquantity(ies) of phosphorous oxyacid salt(s) to water, by adding thedesired quantity of a base such as an alkali metal hydroxide to asolution of the phosphorous oxyacid, by adding the desired quantity ofphosphorous oxyacid to a solution of alkali metal hydroxide, or bymixing a phosphorous oxyacid with one or more phosphorous oxyacid salts.Other bases, such as ammonia, may be used to neutralize the phosphorousoxyacid.

[0022] Preferred aqueous solutions of phosphorous oxyacid salts used inthe process of the present invention may have a pH in the range of fromabout 6 to about 10. Fluorinated hydrocarbons having relatively acidichydrogen substituents, that is those having acidity constants (pK_(a))of about 25 or less, may require the use of basic aqueous solutionshaving a pH in the range of about 6 to about 8, while for less reactivefluorinated hydrocarbons, the pH of the aqueous solution may reach 10without formation of significant amounts of unsaturated by-products. Asillustrated in the present examples, use of aqueous solutions ofphosphorous oxyacid salts or other basic salts having a pH greater than10 may result in a significant conversion of a saturated fluorinatedhydrocarbon to an unsaturated compound, or in hydrolysis of anunsaturated fluorinated hydrocarbon. The formation of unsaturatedcompounds may be detected by analysis of the fluorinated hydrocarbon. Inaddition, the formation of unsaturated impurities from saturatedfluorinated hydrocarbons, as well as the hydrolysis of unsaturatedfluorinated hydrocarbons, is accompanied by the appearance of halideions (e.g., fluoride or chloride) in the recovered aqueous solutions.

[0023] Because phosphorous oxyacid salts form buffer solutions, the useof these materials for the process of this invention in the preferred pHrange is advantageous compared with use of highly basic compounds (suchas sodium hydroxide or potassium hydroxide) in the same pH range,because a high degree of pH monitoring is not necessary.

[0024] Acidic contaminants that may be removed from fluorinatedhydrocarbons of this invention are the inorganic acids HF, HCl, HBr, HI,HNO₃ and H₂SO₄. The present process is especially useful for reducing orremoving the acidic contaminants HF and HCl, which are often otherwisedifficult to remove from fluorinated hydrocarbons. These contaminantsarise from previous processing steps which involve these acids directlyor as by-products such as in reactions with HF (fluorination), chlorineand HF (chlorofluorination), chlorine (chlorination), bromine(bromination), hydrogen (such as hydrodechlorination orhydrodefluorination), or with sulfuric acid (such as in HF recovery).

[0025] Saturated acyclic fluorinated hydrocarbons of the presentinvention are compounds represented by the formulaC_(a)H_(b)F_(c)W_(d)R_(e), wherein a is an integer from 1 to 10, b is aninteger at least 1, c is an integer at least 1, d is an integer from 0to 10, e is an integer from 0 to 4, the sum of b, c, d, and e is equalto 2a+2, and wherein: W is selected from the group consisting of Cl, Br,and I; R is functional group selected from the group consisting of aryl,C₁-C₁₂ alkyl, C₁-C₁₂ polyhaloalkyl, C₂-C₁₂ alkenyl, C₂-C₁₂polyhaloalkenyl, C₂-C₁₂ alkynyl, C₃-C₁₂ polyhaloalkynyl, C(O)R¹, CO₂R¹,C(O)H, CN, NO₂, OR¹, O₂CR¹, and SO₂R¹; and R¹ is aryl, C₁-C₆ alkyl, andC₁-C₆ polyhaloalkyl.

[0026] Saturated cyclic fluorinated hydrocarbons of the presentinvention are compounds represented by the formulaC_(f)H_(g)F_(h)W_(i)R_(j), wherein f is an integer from 3 to 6, g is aninteger at least 1, h is an integer at least 1, i is an integer from 0to 10, j is an integer from 0 to 4, the sum of g, h, i, and j is equalto 2f, and W and R are as defined earlier herein for the presentsaturated acyclic fluorinated hydrocarbons.

[0027] Unsaturated acyclic fluorinated hydrocarbons of the presentinvention are compounds represented by the formulaC_(n)H_(p)F_(q)W_(r)R_(s), wherein n is an integer from 2 to 6, p is aninteger from 0 to 11, q is an integer at least 1, r is an integer from 0to 8, s is an integer from 0 to 4, the sum of p, q, r, and s is equal to2n, and W and R are as defined earlier herein for the present saturatedacyclic fluorinated hydrocarbons.

[0028] Unsaturated cyclic fluorinated hydrocarbons of the presentinvention are compounds represented by the formulaC_(t)H_(u)F_(v)W_(x)R_(y), wherein t is an integer from 3 to 6, u is aninteger from 0 to 9, v is an integer at least 1, x is an integer from 0to 8, and y is an integer from 0 to 4, the sum of u, v, x, and y isequal to 2t-2, and where W and R are as defined earlier herein for thepresent saturated acyclic fluorinated hydrocarbons.

[0029] More preferably, the process of the present invention is carriedout wherein said at least one fluorinated hydrocarbon is selected fromthe group consisting of: (i) saturated acyclic fluorinated hydrocarbonsof the formula C_(a)H_(b)F_(c), wherein a is an integer from 1 to 10, bis an integer from 1 to 21, c is an integer from 1 to 21, and the sum ofb and c is equal to 2a+2, (ii) saturated cyclic fluorinated hydrocarbonsof the formula C_(f)H_(g)F_(h), wherein f is an integer from 3 to 6, gis an integer from 1 to 11, h is an integer from 1 to 11, and the sum ofg and h is equal to 2f, (iii) unsaturated acyclic fluorinatedhydrocarbons of the formula C_(n)H_(p)F_(q), wherein n is an integerfrom 2 to 6, p is an integer from 0 to 11, q is an integer from 1 to 12,and the sum of p and q is equal to 2n, and (iv) unsaturated cyclicfluorinated hydrocarbons of the formula C_(t)H_(u)F_(v), wherein t is aninteger from 3 to 6, u is an integer from 0 to 9, v is an integer from 1to 10, and the sum of u and v is equal to 2t-2.

[0030] The present inventive process is especially suitable forsaturated, acyclic or cyclic, fluorinated hydrocarbons having relativelyacidic hydrogen substituents. The acidity of the hydrogen substituentsis influenced by the presence of electron-withdrawing substitutents,such as halogens or polyhaloalkyl groups such as CF₃, in the molecule.Such compounds are characterized by pK_(a) values in the range of fromabout 11 to about 25 as discussed by Smart on pages 988 to 989 ofChemistry of Organic Fluorine Compounds II, edited by M. Hudlicky and A.E. Pavlath, ACS Monograph 187, American Chemical Society, Washington,D.C. (1995), and by Reutov, Beletskaya, and Butin on pages 51 to 58 inCH-Acids, Pergamon Press, Oxford (1978). These compounds are alsocharacterized by halogen substitution patterns which have vicinalhydrogen and halogen substitutents that allow the possibility of facileelimination of hydrogen halide in the presence of a strong base.Examples of substitution patterns that promote easy elimination ofhydrogen halide in the presence of strong base include acyclic andcyclic compounds having the following structural features: —CHZCHZ—,—CZ₂CHZ—, —CH₂CHZ—, —CZ₂CH₂—, CZ₃CHZ—, and CZ₃CH₂—where Z isindependently selected from the group consisting of F, Cl, Br, and I. Inparticular, compounds such as HFC-236fa, HCFC-235fa (CF₃CH₂CClF₂), andHFC-245fa which have the structural feature —CZ₂CH₂CZ₂—, aresurprisingly reactive toward aqueous solutions having a pH greater thanabout 10.

[0031] Representative saturated acyclic fluorinated hydrocarbons of thepresent invention, compounds that are relatively acidic and susceptibleto elimination of HF include, but are not limited to,1,1,1,2,3,3,3-heptafluoropropane (CF₃CHFCF₃, HFC-227ea),1,1,1,3,3,3-hexafluoropropane (CF₃CH₂CF₃, HFC-236fa),1,1,1,2,3,3-hexafluoropropane (CF₃CHFCHF₂, HFC-236ea),1,1,1,3,3-pentafluoropropane (CF₃CH₂CHF₂, HFC-245fa),1,1,1,2,3-pentafluoropropane (CF₃CHFCH₂F, HFC-245eb),1,1,2,3,3-pentafluoropropane (CHF₂CHFCHF₂, HFC-245ea),1,1,1,3-tetrafluoropropane (CF₃CH₂CH₂F, HFC-254fb),1,1,1,3,3,3-hexafluoro-2-trifluoromethylpropane ((CF₃)₃CH, HFC-356mz),1,1,1,2,2,4,4,4-octafluorobutane (CF₃CF₂CH₂CF₃, HFC-338mf),1,1,1,3,3-pentafluorobutane (CH₃CF₂CH₂CF₃, HFC-365mfc),1,1,1,2,2,3,4,5,5,5-decafluoropentane (CF₃CHFCHFCF₂CF₃, HFC-43-10mee),1,1,1,2,2,4,4,5,5,5-decafluoropentane (CF₃CF₂CH₂CF₂CF₃, HFC-43-10mcf),1,1,1,2,2,3,3,5,5,5-decafluoropentane (CF₃CH₂CF₂CF₂CF₃, HFC-43-10mf),and 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tridecafluoroheptane(CF₃CF₂CHFCHFCF₂CF₂CF₃, HFC-63-14mcee). Representative saturated cyclicfluorinated hydrocarbons of the present invention, compounds that arerelatively acidic and susceptible to elimination of HF include, but arenot limited to, 1,1,2,2,3,3,4,4,5-nonafluorocyclopentane(cyclo-CHFCF₂CF₂CF₂CF₂—), 1,1,2,2,3,3,4,5-octafluorocyclopentane(cyclo-CHFCHFCF₂CF₂CF₂—), 1,1,2,2,3,3,4-heptafluorocyclopentane(cyclo-CH₂CHFCF₂CF₂CF₂—).

[0032] Representative examples of saturated acyclic fluorinatedhydrocarbons of the present invention substituted with other halogens orfunctional groups which are relatively acidic and susceptible toelimination of HY (hydrogen halide) include, but are not limited to,1,1,2-trichloro-2,2-difluoroethane (CHCl₂CClF₂, HCFC-122),2,2-dichloro-1,1,1-trifluoroethane (CHCl₂CF₃, HCFC-123),2,3-dichloro-1,1,1,3,3-pentafluoropropane (CF₃CHClCClF₂, HCFC-225da),2-chloro-1,1,1,3,3,3-hexafluoropropane (CF₃CHClCF₃, HCFC-226da),3-chloro-1,1,1,2,3,3-hexafluoropropane (CF₃CHFCClF₂, HCFC-226ea),2,3,3-trichloro-1,1,1-trifluoropropane (CF₃CHClCHCl₂, HCFC-233da),2,3-dichloro-1,1,1,3-tetrafluoropropane (CF₃CHClCHClF, HCFC-234da),3-chloro-1,1,1,3,3-pentafluoropropane (CF₃CH₂CClF₂, HCFC-235fa),2-chloro-1,1,1,3,3-pentafluoropropane (CF₃CHClCHF₂, HCFC-235da),2,3-dichloro-1,1,1-trifluoropropane (CF₃CHClCH₂Cl, HCFC-243db),3-chloro-1,1,1,3-tetrafluoropropane (CF₃CH₂CHClF, HCFC-244fa),2,3-dibromo-1,1,1,3,3-pentafluoropropane (CF₃CHBrCBrF₂),2,3-dibromo-1,1,1-trifluoropropane (CF₃CHBrCH₂Br),2,3-dibromo-1,1,1,3-tetrafluoropropane (CF₃CHBrCHBrF),1,1,1,2,3,3-hexafluoro-3-methoxypropane (CF₃CHFCF₂OCH₃),1,1,1,2-tetrafluoro-2-methoxyethane (CF₃CHFOCH₃),1,1,2-trifluoro-1-methoxy-2-trifluoromethoxyethane (CH₃OCF₂CHFOCF₃),1,1,1-trifluoro-2-difluoromethoxyethane (CF₃CH₂OCHF₂),1,1,1-trifluoro-2-trifluoromethoxyethane (CF₃CH₂OCF₃),1,1,1,2-tetrafluoro-2-trifluoromethoxyethane (CF₃CHFOCF₃),1,1,1,2-tetrafluoro-2-difluoromethoxyethane (CF₃CHFOCHF₂),2,3,3,3-tetrafluoropropionitrile (CF₃CHFCN), and methyl3,3,3-trifluoropropionate (CF₃CHFCO₂CH₃).

[0033] Representative acyclic and cyclic unsaturated fluorinatedcompounds of the present invention, compounds that can undergonucleophilic attack and/or hydrolysis, include tetrafluoroethylene(CF₂═CF₂, TFE), hexafluoropropene (CF₃CF═CF₂, HFP),1,1,3,3,3-pentafluoro-1-propene (CF₃CH═CF₂, HFC-1225zc),1,1,2,3,3-pentafluoro-1-propene (CHF₂CF═CF₂, HFC-1225yc),2-chloro-1,1,3,3,3-pentafluoro-1-propene (CF₃CCl═CF₂, CFC-1215xc), andhexafluorocyclobutene (cyclo-C₄F₆).

[0034] The process of the present invention is also useful for reducingthe concentration of acidic contaminants from a mixture comprisingsaturated and unsaturated fluorinated hydrocarbons without substantialdegradation of said saturated and unsaturated fluorinated hydrocarbons.Examples of mixtures of saturated hydrofluorocarbons and unsaturatedfluorinated hydrocarbons which may be treated to remove acidiccontaminants by the process of this invention include, but are notlimited to, mixtures of HFC-227ea and HFP, mixtures of HFC-236fa andHFC-1225zc, mixtures of HFC-236ea and HFC-1225ye, mixtures of HFC-245faand HFC-1234ze (CF₃CH═CHF), mixtures of HFC-227ea, HFC-236fa, HFP, andHFC-1225zc, mixtures of HFC-227ea, HFC-245fa, HFP, and HFC-1234ze, andmixtures of HFC-236fa, HFC-245fa, HFC-1234ze, and HFC-1225zc.

[0035] The present invention is also suitable for removing acidiccontaminants from mixtures of saturated and/or unsaturated fluorinatedhydrocarbons in which the acidic contaminants are present as anazeotrope with one or more of the fluorinated hydrocarbons. Examples ofazeotropes of inorganic acids and fluorinated hydrocarbons which may betreated to remove the acidic contaminant by the process of thisinvention include, but are not limited to, the HF azeotrope of HFC-227eaas described in U.S. Pat. No. 6,376,727, the HF azeotrope of HFC-236eaas described in U.S. Pat. No. 5,563,304, the HF azeotrope of HFC-236faas described in U.S. Pat. No. 5,563,304, the HF azeotrope of HCFC-235faas described in U.S. Pat. No. 6,291,730, and the HF azeotrope ofHFC-245fa as described in U.S. Pat. No. 6,291,730.

[0036] The contacting step of the present invention in which a mixturecontaining one or more fluorinated hydrocarbons and one or more acidiccontaminants is contacted with an aqueous solution of salts ofphosphorous oxyacids may be accomplished by any one of several methodsusing well-known chemical engineering practices for scrubbing organiccompounds. This step may be carried out in batch or continuous mode. Inone embodiment of the invention, the mixture containing theacid-contaminated fluorinated hydrocarbon may be contacted with theaqueous solution under a suitable amount of pressure to maintain aliquid phase of the fluorinated hydrocarbon in the contacting vessel.The contents of the vessel may be agitated to provide contact betweenthe aqueous solution and the fluorinated hydrocarbon. The fluorinatedhydrocarbon is then collected as a lower layer from the vessel orrecovered by distillation.

[0037] In another embodiment of the present process, the mixturecontaining the acid-contaminated fluorinated hydrocarbon may be bubbledinto the aqueous solution as a gas in a stirred tank reactor. Thefluorinated hydrocarbon is then allowed to leave the reactor, optionallythrough a condenser, where it is collected for subsequent purification.

[0038] In a preferred embodiment of the present invention, thecontacting step is conducted in a column packed with materials such ashelices, rings, saddles, spheres or other formed shapes fabricated fromglass, plastic, or ceramics. The mixture of fluorinated hydrocarbon(s)and acidic contaminant(s) enters the bottom of the column as a vapor.The aqueous solution enters the top of the column, for example, by meansof a pump connected to a reservoir of said aqueous solution. The acidiccontaminant(s) in the fluorinated hydrocarbon then reacts with theaqueous solution in the column and the fluorinated hydrocarbon vapor,with reduced acidic contaminant, passes out the top of the column and isthen collected. The aqueous solution passes out the bottom of the columnand returns to the reservoir.

[0039] The aqueous solution may be used until its pH drops to apre-determined point typically from about 6 to about 7. The aqueoussolution is then replaced or treated with additional base, such aspotassium hydroxide, to bring the pH to the desired value. Therestoration of the pH may continue until the concentration of salts inthe aqueous solution reaches the desired value, usually not to exceedabout 20 weight percent.

[0040] The pressure during the contacting steps is not critical, thoughatmospheric and superatmospheric pressures are preferred. Operating theprocess under pressure may be advantageous for subsequent purificationsteps such as distillations.

[0041] The temperature during the contacting step of the mixturecontaining the fluorinated hydrocarbon(s) and acidic contaminant(s) withthe aqueous solution of phosphorous oxyacid salts is not critical andmay take place at temperatures of from about 0° C. to about 100° C.,preferably from about 25° C. to about 80° C. Lower temperatures thanabout 25° C. may result in loss of fluorinated hydrocarbon due tocondensation or to solubility in the aqueous phase. Temperatures higherthan about 80° C. increase the rate of undesirable elimination processesas observed by increased levels of unsaturated impurities in thefluorinated hydrocarbon and increased levels of halide ion (e.g.,fluoride) in the aqueous phase.

[0042] The time of contact between the mixture of the fluorinatedhydrocarbon and the aqueous solution is not critical and typically maybe on the order of about 30 seconds to about an hour. In the preferredembodiment of the invention, the contact time may be typically fromabout 30 seconds to about 10 minutes.

[0043] In the recovering step of the process of the present invention,fluorinated hydrocarbon product(s) that has been freed of the acidcontaminant(s) is delivered to a separation unit for recovery. Thefluorinated hydrocarbon product will typically be separated from waterby means of a decanter, by distillation, or by drying with a molecularsieve or anhydrous salt (for example, calcium sulfate), or by acombination thereof. The fluorinated hydrocarbon product may then befurther purified by distillation.

[0044] Without further elaboration, it is believed that one skilled inthe art can, using the description herein, utilize the present inventionto its fullest extent. The following specific embodiments are,therefore, to be construed as merely illustrative, and do not constrainthe remainder of the disclosure in any way whatsoever.

EXAMPLES

[0045] LEGEND 123 is CF₃CHCl₂ 225da is CF₃CHClCClF₂ 227ea is CF₃CHFCF₃235fa is CF₃CH₂CClF₂ 236ea is CF₃CHFCHF₂ 236fa is CF₃CH₂CF₃ 245fa isCF₃CH₂CHF₂ 365mfc is CF₃CH₂CF₂CH₃ 43-10mee is CF₃CHFCHFCF₂CF₃ 1225zc isCF₃CH═CF₂ HFP is CF₃CF═CF₂

[0046] Preparation of Solutions of Aqueous Bases

[0047] Preparation of 6.5:1 Na₂HPO₄/NaH₂PO₄ Solutions

[0048] A 20 wt % stock solution of 6.5:1 Na₂HPO₄/NaH₂PO₄ (mole basis)was prepared by adding 14.90 g (0.09552 mole) NaH₂PO₄[2(H₂O)] and 88.55g (0.6238 mole) Na₂HPO₄ to a flask and bringing the total weight to500.0 g with deionized water. The solution was 2.29 wt % NaH₂PO₄ (basedon the anhydrous salt) and 17.71 wt % Na₂HPO₄. The 20% buffer stocksolution prepared above was then diluted 1 to 5 by weight with water togive a 4 wt % buffer solution (3.54 wt % Na₂HPO₄, 0.458 wt % NaH₂PO₄)having a pH of 7.54.

[0049] Preparation of 5.7:1 K HPO₄/KH₂PO₄ Solutions

[0050] 136.4 g (1.193 mole) of H₃PO₄ (85.7%) was diluted with 400.7 g ofwater in a large Erlenmeyer flask. The resulting acid solution wastreated dropwise with 412.9 g (2.208 mole) of 30 wt % KOH (prepared bydissolving 171.8 g of 87.3% KOH pellets in 328.2 g of DI water). Theaddition funnel was rinsed into the final solution with an additional50.0 g of water. The resulting solution is about 17.7 wt % K₂HPO₄ and2.4 wt % KH₂PO₄. A 4 wt % potassium phosphate buffer solution wasprepared by diluting the 20 wt % buffer 1 to 5 with water; the pH of thesolution was 7.43.

[0051] Preparation of 6:1 K₂HPO₄/KH₂PO₄ Solutions

[0052] 17.70 g (0.102 mole) of K₂HPO₄ and 2.30 g (0.0169 mole) of KH₂PO₄were dissolved in water and brought to a total weight of 100 g. Theresulting solution was diluted 1 to 5 with water to give a 4% (w/w)solution having a pH of 7.92.

[0053] Preparation of 98:2 K₂HPO₄/K₃PO₄ Solutions

[0054] 19.515 g (0.112 mole) of K₂HPO₄ and 0.485 g (0.00228 mole) ofK₃PO₄ were dissolved in water and brought to a total weight of 100 g.The resulting solution was diluted 1 to 5 with water to give a 4% (w/w)solution having a pH of 9.93.

[0055] Preparation of 1:1 K₂HPO₄/K₃PO₄ Solutions

[0056] 9.015 g (0.0518 mole) of K₂HPO₄ and 10.985 g (0.0517 mole) ofK₃PO₄ were dissolved in water and brought to a total weight of 100 g.The resulting solution was diluted 1 to 5 with water to give a 4% (w/w)solution having a pH of 11.86.

[0057] Preparation of 6% Na₂CO₃/3% Na₂SO₃ Solution

[0058] 10.5 g (0.0991 mole) of Na₂CO₃ and 5.25 g (0.0417 mole) of Na₂SO₃were dissolved in water (159.25 g). The pH of the resulting solution was11.63.

[0059] Preparation of 2% Na₂CO₃ Solution

[0060] 3.5 g (0.0330 mole) of Na₂CO₃ were dissolved in water (171.5 g).The pH of the resulting solution was 11.49.

[0061] Preparation of 2% Na₂SO₃ Solution

[0062] 3.5 g (0.0278 mole) of Na₂SO₃ were dissolved in water (171.5 g).The pH of the resulting solution was 10.04.

[0063] General Procedure for Assessing Reactivity of Hydrofluorocarbonswith Basic Aqueous Solutions

[0064] The reactivity of various hydrofluorocarbons with bases wasassessed by contacting a mixture of the two in sealed tubes (shakertubes) or in a counter-current scrubber at a specified temperature for aspecified period of time. The recovered hydrofluorocarbon was analyzedby GC. The recovered aqueous phases was weighed, purged with nitrogen toexpel any dissolved hydrofluorocarbon, and the pH determined. Thechloride ion concentration in the aqueous phase was determined by meansof ion selective electrode. The fluoride ion concentration in theaqueous phase was determined by means of an ion selective electrode orion chromatography using authentic fluoride standards to calibrate themethods. Time average rates of decomposition of the fluorocarbons werebased on the concentrations of fluoride in the aqueous phase and thetime of agitation of the shaker tube or the time of fluorinatedhydrocarbon gas flow through the counter-current scrubber.

[0065] General Procedure for Shaker Tube Tests

[0066] A 400 mL stainless steel shaker tube was charged with 175.0 g ofaqueous base. The shaker tube was sealed, cooled in dry ice, evacuated,and purged with nitrogen. The tube was re-evacuated and charged with25.0 g of hydrofluorocarbon. The tube was then placed in the shakermechanism and brought to the desired temperature with agitation. Itgenerally took 1-1.5 hours to bring the cold tube to the temperature setpoint. The tube was then held at the desired temperature (either 40° C.or 100° C.) for 0.5 hour. After 0.5 hour, agitation was ceased and thetube was cooled in a stream of air. It typically took at least 0.5 hourto cool the tube. If the hydrofluorocarbon was a gas at roomtemperature, it was collected in an evacuated 300 mL cylinder chilled indry ice. If the hydrofluorocarbon was a liquid at room temperature, itwas discharged with the aqueous phase from the shaker tube and thenseparated as a liquid.

[0067] The results of contacting several fluorinated hydrocarbons withbasic solutions in shaker tubes are given in Table 1. “C” (e.g., C1)example numbers are comparative examples.

[0068] General Procedure for Counter-current Scrubber Tests

[0069] The counter-current scrubber consisted of an 46 cm×2.5 cm i.d.Pyrex™ glass tube packed with 7×7 mm Raschig rings connected to a 5Lflask which served as a reservoir for the scrubbing medium. A variablespeed peristaltic pump circulated the scrubbing solution from thereservoir to the top of the column. The test gas entered the vapor spaceof the reservoir and moved up through the packed column where itcontacted the basic media. The scrubbed hydrofluorocarbon gas passedthrough a drying tube packed with anhydrous calcium sulfate andcondensed in a cylinder immersed in dry ice.

[0070] The reservoir was charged with about 1 kg of scrubbing media. Thereactor system was purged with nitrogen at 100 sccm (1.7×10⁻⁶ m³/s) withthe pump feeding caustic at 100 mL/min while the temperature of thecaustic in the reservoir was brought to temperature (typically 60±2°C.). The nitrogen flow was then replaced with the fluorocarbon at a flowrate of 100 sccm (1.7×10⁻⁶ m³/s). Hydrofluorocarbon was fed to thescrubber for 2 to 3 hours; the pressure in the system was about twoinches of water (0.0049 atm). The hydrofluorocarbon flow was thenstopped and the system purged with nitrogen while the causticrecirculation rate was increased to about 400 mL/min. The contents ofthe reservoir were then discharged, weighed, the pH measured, andanalyzed for fluoride ion content. The hydrofluorocarbon recovered inthe collection cylinder was analyzed by GC-MS. The results of contactingHFC-236fa and HFC-245fa with basic solutions in a counter-currentscrubber are given in Table 2. “C” (e.g., C1) example numbers arecomparative examples. TABLE 1 Alkaline Hydrolysis of FluorinatedHydrocarbons in Shaker Tubes^(a) Aqueous Average % % Unsaturates ExampleTemperature/ Phase^(e) ppm Aqueous Decomposition in Fluorinated No.Substrate^(b) Scrubbing Media^(c) Time^(d) ° C./hours Cl Phase^(e) ppm FPer Hour^(f) Hydrocarbon^(g)  1 123   6% NaH₂PO₄ 50/8  7.7 0.5 0.0032nd^(k) C1 123   6% Na₂CO₃/ 50/2  19200 <1000 33.1 15   3% Na₂SO₃ C2 123  6% KOH 50/2  28900 1500 49.8 86  2 225da   6% NaH₂PO₄ 50/8  116 8.60.057 0.3 C3 225da   6% Na₂CO₃/ 50/2  22800 4300 47.6 94   3% Na₂SO₃ C4225da   6% KOH 50/2  20000 4400 41.2 27  3 227ea 3.54% K₂HPO₄/  40/0.5nd 2.0 0.025^(h) 0.0008 0.46% KH₂PO₄  4 227ea 3.54% K₂HPO₄/  100/0.5  nd1.7 0.021^(h) 0.046 0.46% KH₂PO₄ C5 227ea   5% KOH  40/0.5 nd 49.10.61^(h) 0.011 C6 227ea   5% KOH  100/0.5  nd 10440 21.9^(i) 0.29  5235fa   6% NaH₂PO₄ 50/8  1.2 0.1 0.000041 0.06  6 235fa   4% KH₂PO₄ 80/0.5 32 <0.5 0.21 nd C7 235fa   6% Na₂CO₃/ 25/4  833 700 0.68 0.12  3% Na₂SO₃ C8 235fa   2% Na₂CO₃  40/0.5 1219 161 8.0 0.58 C9 235fa   2%Na₂SO₃  40/0.5 1066 102 7.0 0.34  7 236ea   6% NaH₂PO₄ 50/8  nd 0.10.000069 not measured  8 236ea 3.54% K₂HPO₄/  40/0.5 nd 0.75 0.0082 0.050.46% KH₂PO₄ C10 236ea   6% Na₂CO₃/ 50/2  nd 52 0.14 not measured   3%Na₂SO₃ C11 236ea   5% KOH  40/0.5 nd 625 6.87 3.  9 236fa   4% KH₂PO₄ 80/0.5 2.0 <0.5 0.0055^(h) 0.003 10 236fa   2% Na₂HPO₄/  80/0.5 14.0<0.5 0.0055^(h) 0.0047   2% KH₂PO₂ C12 236fa   6% Na₂CO₃/ 25/4  nd 18.80.0043^(i) 0.023   3% Na₂SO₃ C13 236fa   6% Na₂CO₃/ 50/2  nd 71.90.033^(i) 0.085   3% Na₂SO₃ C14 236fa   2% Na₂CO₃  80/0.5 <5.0 5781.1^(i) 1.6 C15 236fa   5% KOH  40/0.5 nd 2330 4.3^(i) 0.4 11 245fa3.54% K₂HPO₄/  40/0.5 nd 1.4 0.0135 0.48 0.46% KH₂PO₄ 12 245fa 3.54%K₂HPO₄/  100/0.5  nd 37 0.357 0.63 0.46% KH₂PO₄ C16 245fa   5% KOH 40/0.5 nd 958 9.27 4.7 C17 245fa   5% KOH  100/0.5  nd 14752 145.7 7313 HFP 3.54% K₂HPO₄/  40/0.5 nd 9.1 0.049 nd 0.46% KH₂PO₄ 14 HFP 3.54%K₂HPO₄/  100/0.5  nd 854 4.64 nd 0.46% KH₂PO₄ C18 HFP   5% KOH  40/0.5nd 9640 54.8 nd C19 HFP   5% KOH  100/0.5  nd 8750 49.5 nd 15 1225zc  6% NaH₂PO₄ 50/8  63 2.5 0.00073^(h) nd 16 1225zc 3.54% K₂HPO₄/  40/0.5nd 9.0 0.043^(h) nd 0.46% KH₂PO₄ 17 1225zc 3.54% K₂HPO₄/  100/0.5  nd990 4.8^(h) nd 0.46% KH₂PO₄ C20 1225zc   6% Na₂CO₃/ 25/4  173 56501.4^(i) nd   3% Na₂SO₃ C21 1225zc   5% KOH  40/0.5 nd 9880 19.5^(i) nd18 365mfc 3.54% K₂HPO₄/  40/0.5 nd 13 0.14 j 0.46% KH₂PO₄ 19 365mfc3.54% K₂HPO₄/  100/0.5  nd 5 0.054 0.08 0.46% KH₂PO₄ C22 365mfc   5% KOH 40/0.5 nd 350 3.85 0.49 C23 365mfc   5% KOH  100/0.5  nd 14,130 158 5320 43-10mee 3.54% K₂HPO₄/  40/0.5 nd 8.0 0.15 0.015 0.46% KH₂PO₄ C2443-10mee   5% KOH  40/0.5 nd 5,000 91.4 46 #moles fluorocarbon = (Wt.Fluorocarbon fed, grams)/(Mol. Wt.); At. Wt. = atomic weight of halide.Decomposition rates based on chloride analysis for HCFC-122, −225da, and−235fa; fluoride analysis used for all others.

[0071] TABLE 2 Alkaline Hydrolysis of Fluorinated Hydrocarbons inCounter-current Scrubbers^(a) Average % % Unsaturate Example FluorideDecomposition in Fluorinated No. Substrate^(b) Scrubbing Media^(c)pH^(d) Level^(e) (ppm) Per Hour^(f) Hydrocarbon^(g) C25 236fa 5% NaOH13.09 1380 0.50 0.066 21 236fa 4% 1:1 K₂HPO₄:K₃PO₄ 11.89 120 0.044 0.03822 236fa 4% 98:2 K₂HPO₄:K₃PO₄ 9.65 1 0.00038 0.017 23 236fa 4% 6:1K₂HPO₄:KH₂PO₄ 7.83 0.5 0.00017 0.019 C26 245fa^(h) 5% NaOH 13.8 1497 8.516.6 24 245fa^(h) 4% 98:2 K₂HPO₄:K₃PO₄ 9.88 11.4 0.062 0.14 25 245fa^(h)4% 6:1 K₂HPO₄:KH₂PO₄ 7.64 4.1 0.016 0.24 #for 236fa and 227ea, f = 5 for1225zc and HFP; f = 1 for 245fa; moles fluorocarbon = (Wt. Fluorocarbonfed)/(Mol. Wt.); 19 = atomic weight of fluorine; Run time = 3 hours

1. A process for reducing the concentration of at least one acidiccontaminant selected from the group consisting of HF, HCl, HBr, HI, HNO₃and H₂SO₄ in a mixture of at least one fluorinated hydrocarbon and saidat least one acidic contaminant, comprising: contacting said mixturewith at least one phosphorous oxyacid salt, wherein if said salt is inaqueous solution, said aqueous solution has a pH of no more than about10, and recovering said at least one fluorinated hydrocarbon havingreduced concentration of said at least one acidic contaminant, providedthat said at least one fluorinated hydrocarbon is not CF₃CH₂CF₃ orCF₃CHFCF₃.
 2. The process of claim 1 wherein said at least one acidiccontaminant is selected from the group consisting of HF and HCl.
 3. Theprocess of claim 1 wherein said at least one fluorinated hydrocarbon isselected from the group consisting of: (i) saturated acyclic fluorinatedhydrocarbons of the formula C_(a)H_(b)F_(c)W_(d)R_(e), wherein a is aninteger from 1 to 10, b is an integer at least 1, c is an integer atleast 1, d is an integer from 0 to 10, e is an integer from 0 to 4, andthe sum of b, c, d, and e is equal to 2a+2, (ii) saturated cyclicfluorinated hydrocarbons of the formula C_(f)H_(g)F_(h)W_(i)R_(j),wherein f is an integer from 3 to 6, g is an integer at least 1, h is aninteger at least 1, i is an integer from 0 to 10, j is an integer from 0to 4, and the sum of g, h, i, and j is equal to 2f, (iii) unsaturatedacyclic fluorinated hydrocarbons of the formulaC_(n)H_(p)F_(q)W_(r)R_(s), wherein n is an integer from 1 to 6, p is aninteger from 0 to 11, q is an integer at least 1, r is an integer from 0to 8, s is an integer from 0 to 4, and the sum of p, q, r, and s isequal to 2n, and (iv) unsaturated cyclic fluorinated hydrocarbons of theformula C_(t)H_(u)F_(v)W_(x)R_(y), wherein t is an integer from 3 to 6,u is an integer from 0 to 9, v is an integer at least 1, x is an integerfrom 0 to 8, y is an integer from 0 to 4, and the sum of u, v, x, and yis equal to 2t-2, wherein: W is selected from the group consisting ofCl, Br, and I; R is selected from the group consisting of aryl, C₁-C₁₂alkyl, C₁-C₁₂ polyhaloalkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ polyhaloalkenyl,C₂-C₁₂ alkynyl, C₃-C₁₂ polyhaloalkynyl, C(O)R¹, CO₂R¹, C(O)H, CN, NO₂,OR¹, O₂CR¹, and SO₂R¹; and R¹ is selected from the group consisting ofaryl, C₁-C₆ alkyl, and C₁-C₆ polyhaloalkyl.
 4. The process of claim 3wherein said at least one fluorinated hydrocarbon is selected from thegroup consisting of: (i) saturated acyclic fluorinated hydrocarbons ofthe formula C_(a)H_(b)F_(c), wherein a is an integer from 1 to 10, b isan integer from 1 to 21, c is an integer from 1 to 21, and the sum of band c is equal to 2a+2, (ii) saturated cyclic fluorinated hydrocarbonsof the formula C_(f)H_(g)F_(h), wherein f is an integer from 3 to 6, gis an integer from 1 to 11, h is an integer from 1 to 11, and the sum ofg and h is equal to 2f, (iii) unsaturated acyclic fluorinatedhydrocarbons of the formula C_(n)H_(p)F_(q), wherein n is an integerfrom 2 to 6, p is an integer from 0 to 11, q is an integer from 1 to 12,and the sum of p and q is equal to 2n, and (iv) unsaturated cyclicfluorinated hydrocarbons of the formula C_(t)H_(u)F_(v), wherein t is aninteger from 3 to 6, u is an integer from 0 to 9, v is an integer from 1to 10, and the sum of u and v is equal to 2t-2.
 5. The process of claim4 wherein said at least one fluorinated hydrocarbon is CF₃CH₂CHF₂. 6.The process of claim 1 wherein said at least one phosphorous oxyacidsalt is in aqueous solution during said contacting.
 7. (cancelled). 8.The process of claim 1 wherein said at least one phosphorous oxyacidsalt is selected from the group consisting of: (i) orthophosphoric acidsalts of the formula M_(n)H_(3-n)PO₄, wherein n is an integer from 1 to3; (ii) phosphorous acid salts of the formula M_(m)H_(2-m)(HPO₃),wherein m is 1 or 2; (iii) metaphosphoric acid salts of the formula(MPO₃)_(z), wherein z is an integer from 1 to 6; and (iv) pyrophosphoricacid salts of the formula M_(k)H_(4-k)P₂O₇, wherein k is an integer from1 to 4, wherein M is selected from the group consisting of NH₄, Li, Na,and K.
 9. The process of claim 8 wherein said at least one phosphorousoxyacid salt is an orthophosphoric acid salt of the formulaM_(n)H_(3-n)PO₄, wherein n is an integer from 1 to 3, and M is selectedfrom the group consisting of NH₄, Na, and K.
 10. The process of claim 1whereby less than about 5 weight percent of said at least onefluorinated hydrocarbon is decomposed by dehydrohalogenation orhydrolysis during said contacting step.
 11. The process of claim 1wherein said mixture is azeotropic or azeotrope-like.
 12. A process forremoving at least one acidic contaminant selected from the groupconsisting of HF and HCl from a mixture of at least one fluorinatedhydrocarbon and said at least one acidic contaminant, comprising:contacting said mixture with an aqueous solution of at least oneorthophosphoric acid salt of the formula M_(n)H_(3-n)PO₄, wherein n isan integer from 1 to 3, and M is selected from the group consisting ofNH₄, Na, and K, said aqueous solution having a pH of no more than about10, and recovering said at least one fluorinated hydrocarbonsubstantially free of said at least one acidic contaminant, wherein saidat least one fluorinated hydrocarbon is selected from the groupconsisting of: (i) saturated acyclic fluorinated hydrocarbons of theformula C_(a)H_(b)F_(c), wherein a is an integer from 1 to 10, b is aninteger from 1 to 21, c is an integer from 1 to 21, and the sum of b andc is equal to 2a+2, (ii) saturated cyclic fluorinated hydrocarbons ofthe formula C_(f)H_(g)F_(h), wherein f is an integer from 3 to 6, g isan integer from 1 to 11, h is an integer from 1 to 11, and the sum of gand h is equal to 2f, (iii) unsaturated acyclic fluorinated hydrocarbonsof the formula C_(n)H_(p)F_(q), wherein n is an integer from 2 to 6, pis an integer from 0 to 11, q is an integer from 1 to 12, and the sum ofp and q is equal to 2n, and (iv) unsaturated cyclic fluorinatedhydrocarbons of the formula C_(t)H_(u)F_(v), wherein t is an integerfrom 3 to 6, u is an integer from 0 to 9, v is an integer from 1 to 10,and the sum of u and v is equal to 2t-2, provided that said at least onefluorinated hydrocarbon is not CF₃CH₂CF₃ or CF₃CHFCF₃.
 13. The processof claim 1 or 12, wherein said at least one fluorinated hydrocarbonobtained from said contacting step contains 10 ppm-molar or less of saidat least one acidic contaminant.